1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly to a semiconductor device provided with a through electrode.
2. Description of the Related Art
In recent years, a Through Silicon Via (hereinafter referred to as TSV) formed by burying an conductive material into a through hole provided in silicon of a semiconductor substrate has been used as a mounting technique for realizing high-integration and high-speed semiconductor devices. The TSV is an electrode penetrating perpendicularly through a semiconductor substrate and is usually formed as a rear bump on the rear side of the semiconductor substrate. An interconnection connected to the rear bump, a front bump connected to the interconnection, which are formed on the front side of the semiconductor substrate, and the rear bump are collectively referred to a through electrode. By mutually connecting the exposed terminals of the through electrodes (the front bump and the rear bump) in stacked semiconductor chips, the degree of integration per unit area occupied by a semiconductor device is improved, and also an interconnection length between the respective semiconductor chips is reduced to thereby increase the operation speed of the semiconductor device. The TSV is connected to a conductive layer (hereinafter referred to as wiring pad) in a semiconductor chip at one end portion (hereinafter referred to as an inner terminal) of a TSV in a semiconductor substrate and is further connected to semiconductor elements of an integrated circuit via the wiring pad (see JP2010-272737A).
Here, the inner terminal of the TSV and the wiring pad in the related art are formed in parallel with the surface of the semiconductor substrate, and are each formed in a flat shape. In this configuration, there has been a case where, when the TSV is expanded or contracted due to heat stress applied in a subsequent step, a gap (void) is generated in the joint surface between the TSV and the wiring pad, so as to increase the electric resistance at the joint surface.